diff --git a/recipes/libbacktrace/recipe.py b/recipes/libbacktrace/recipe.py
index 8733feb..858b849 100644
--- a/recipes/libbacktrace/recipe.py
+++ b/recipes/libbacktrace/recipe.py
@@ -1,8 +1,8 @@
 
 from SCons.Script import *
 
-def cook(env: Environment) -> dict:
-    repo = env.Cook('GitBranch', repo_name = 'libbacktrace', remote_url = 'https://github.com/ianlancetaylor/libbacktrace.git', git_ref = 'master')
+def cook(env: Environment, git_ref = 'master') -> dict:
+    repo = env.Cook('GitBranch', repo_name = 'libbacktrace', remote_url = 'https://github.com/ianlancetaylor/libbacktrace.git', git_ref = git_ref)
     checkout_root = repo['checkout_root']
     build_result = env.Cook('AutotoolsProject', checkout_root)
     return {